This invention generally relates to hand-held plastic containers for storing and dispensing particulate matter. More particularly, it relates to such containers with a cover having a plurality of flaps for enclosing, respectively, a plurality of openings in the cover. More particularly, it relates to containers for foodstuffs having a shaker opening with a plurality of holes and/or a spooning opening with a large opening adapted to receive a common household spoon.
Plastic caps and receptacles for the disposable container industry suffer from certain incompatibilities. Generally speaking, they are considered interchangeable, since they have standard threads and standard major diameters. For this reason, one can expect a nominal xe2x80x9c63 mmxe2x80x9d cap to handily screw onto a xe2x80x9c63 mmxe2x80x9d receptacle. Beyond this, however, one cannot be assured of compatibility. Commercial receptacles or bottles typically have recessed shoulders adjacent to their open threaded ends to receive the threaded skirt of the cap. The goal is to screw a cap with an outer circular diameter onto a bottle with the same unrecessed outer diameter, thereby providing a cylindrical container with a constant outer diameter over its entire height. As a result, when one screws a random cap onto a random bottle, the skirt of the cap may interfere with the unrecessed portion of the bottle before the cap is screwed down. This will prevent the cap from being screwed completely down, thereby preventing the sealing surfaces of the cap from completely engaging the sealing surfaces of the bottle.
In addition to this incompatibility, the diameter and width of the sealing surfaces of the bottle and cap are often different, even when they have the same nominal thread pitch and major diameter. If a manufacturer wishes to make a cap (or bottle) that can be used with the greatest range of bottles (or caps) by other manufacturers, he is compelled to make as wide a sealing surface as possible. Unfortunately, this requires additional plastic.
There is another problem when manufacturing caps with wide sealing flanges: the propensity of the bottle top to buckle when screwed down too tightly. A wide flange permits force to be applied evenly to the top of bottles with warped sealing surfaces. These bottles have sealing surfaces at their mouths that are not truly circular, but are oval. By screwing a cap down firmly onto the bottle, such as with an automatic capping machine, the oval top begins to buckle, with some portions of the bottle bending inward, and some portions of the bottle bending outward. U.S. Pat. No. 4,693,399, which issued to Hickman (Sep. 15, 1987) purported to solve the ovality problem by providing the cap with a wide, flat sealing surface that was wide enough to accommodate a warped, oval-topped bottle. By providing a wide, flat surface against which the bottle could seal, the top of the bottle could be quite oval, yet there would still be sufficiently wide, flat surface against which it could seal. Unfortunately, this arrangement merely accommodated the out-of-roundness of a warped bottle. The tops of the bottles remained warped. This was an effective solution for hand-tightened caps, but was of quite limited value for machine-attached and tightened caps. Machines for attaching caps to bottles operate at high speeds. It is quite difficult to adjust them to provide a constant tightening torque. As a result the torque applied to seal a cap on bottle will vary significantly in a single production run. Given this wide range of tightening torques, the wide flange of the ""399 patent can actual cause bottles to buckle during capping.
As the cap is tightened, the oval rim of the bottle slides against the wide, flat sealing flange, reducing friction between the rim and the wide sealing flange, making it easier to move axially inward or outward, toward or away from the central axis of the bottle. As a result of this reduced friction, the oval rim of the bottle tends to increase in ovality as the bottle is over-tightened until it either disengages from the threads or the bottle collapses.
What is needed is an improved cap that can accommodate a wide range of bottle mouth diameters. What is also needed is a cap that can correct (and not accommodate) bottles with warped oval mouths and sealing surfaces. It is an object of this invention to provide such a cap.
In accordance with a first embodiment of the invention, a circular plastic cap having a longitudinal axis is disclosed, the cap including an end cover, at least one flap integrally formed with the end cover, a cylindrical skirt integrally coupled to the end cover at one end and having a second open end configured to receive the mouth of a receptacle, and a circular sealing ring disposed inside the skirt and adjacent to the end cover, the sealing ring having a plurality of planar sealing surfaces, axially spaced apart, such that each sealing surface has a greater diameter the closer that sealing ring is to the open end of the skirt. Each sealing surface may have an axial width substantially equal to or less than an average thickness of the cap. The sealing ring may include a plurality of substantially right cylindrical surfaces coaxial with the cap disposed between adjacent sealing surfaces.
Each right cylindrical surface may have a greater diameter the preceding right cylindrical surface as one approaches the open end of the skirt. The sealing ring may be fixed to the end cover. The sealing ring may or may not be fixed to the skirt.
In accordance with a second embodiment of the invention, a container is disclosed, the container including a receptacle including a right cylindrical sidewall having an externally threaded upper end and a lower end, a bottom integrally formed with the sidewall and enclosing the lower end of the sidewall, wherein the upper end of the receptacle defines a mouth having a mouth sealing surface, and a circular plastic cap having a longitudinal axis, wherein the cap further comprises an end cover, at least one flap integrally formed with the end cover, a cylindrical skirt integrally coupled to the end cover at one end and having a second open end configured to receive the mouth of a receptacle, and a circular sealing ring disposed inside the skirt and adjacent to the end cover, the sealing ring having a plurality of planar sealing surfaces, axially spaced apart, such that each sealing surface has a greater diameter the closer that sealing ring is to the open end of the skirt, wherein one of the plurality of sealing surfaces is engaged with the mouth sealing surface and at least one of the plurality of sealing surfaces is not engaged with the mouth sealing surface. The end cover and the at least one flap may be configured to provide the cap with a substantially flat planar end surface. The at least one flap may be recessed into and flush with the end cover. The cap may further comprise a second flap, wherein the second flap is integrally formed with the end cover. The second flap may be recessed into and flush with the end cover. Each sealing surface may have an axial width substantially equal to or less than an average thickness of the cap. The sealing ring may include a plurality of substantially right cylindrical surfaces coaxial with the cap disposed between adjacent sealing surfaces. Each right cylindrical surface may have a greater diameter than a preceding right cylindrical surface as one approaches the open end of the skirt. The sealing ring may be fixed to the end cover. The sealing ring may not be fixed to the skirt.
In accordance with a third embodiment of the invention, a method of attaching an sealing a cap to a bottle is disclosed, wherein the cap comprises an end cover; a cylindrical skirt integrally coupled to the end cover at one end and having a second open end configured to receive the mouth of a receptacle, and a circular sealing ring disposed inside the skirt and adjacent to the end cover, the sealing ring having a plurality of planar sealing surfaces, axially spaced apart, such that each sealing surface has a greater diameter the closer that sealing ring is to the open end of the skirt, and wherein the bottle comprises a right cylindrical sidewall having an externally threaded upper end and a lower end, a bottom integrally formed with the sidewall and enclosing the lower end of the sidewall, wherein the upper end of the receptacle defines a mouth having a mouth sealing surface, wherein the method includes gripping the bottle in an automatic capping machine, gripping the cap in an automatic capping machine, rotating the cap clockwise with respect to the bottle while advancing the cap toward the bottle, engaging the external threads on the bottle to the internal threads on the cap, rotating the cap until the mouth sealing surface engages a first of the plurality of sealing surfaces, further rotating the cap until the mouth sealing surface engages a second of the plurality of sealing surfaces, wherein the second of the plurality of sealing surfaces has a smaller diameter than the first of the plurality of sealing surfaces, and sealing the container against the second of the plurality of sealing surfaces. The step of further rotating the cap may include the step of guiding at least a portion of the mouth sealing surface inwardly toward the axis of the cap. The step of further rotating the cap may include the step of deforming the mouth sealing surface into a more circular shape.